#679 CLI submit was not storing Python DSL source code

Bug: When submitting Python DSL workflows via CLI, the python_dsl source was not being passed to the API. The CLI loaded the .py file, compiled it locally via load_python_dsl(), but only sent the compiled workflow_definition JSON. The python_dsl parameter was never populated. Fix: Modified engine/cli/submit.py to: 1. Read the raw Python source code before compilation 2. Pass it to submit_workflow() as python_dsl parameter 3. The API then stores it in DataShard and python_dsl_content column Impact: Workflows submitted via CLI now have their Python DSL source preserved for auditing and retrieval.